The repetitive calcium waves in the fertilized ascidian egg are initiated near the vegetal pole by a cortical pacemaker.
The repetitive calcium waves in the fertilized ascidian egg are initiated near the vegetal pole by a cortical pacemaker.
复制标题
海鞘受精卵中的重复钙波是由皮质起搏器在植物极附近启动的。
DOI：
10.1016/0012-1606(92)90111-s
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发表时间：
1992
影响因子：
2.7
通讯作者：
Speksnijder,JE
中科院分区：
文献类型：
--
作者：
Speksnijder,JE
海鞘卵对受精的反应是一系列重复的钙波，主要来自植物/收缩极区域（J.E.斯佩克斯奈德角Sardet和L. F. Jaffe，1990，Dev. 142，246 -249），其中肌质在卵质分离的第一阶段浓缩。这表明，肌浆可能参与启动这些钙波。为了验证这种可能性，我们在离心分离后，将富含钙的皮层下肌浆部分置换的卵子中，确定了钙波的起始位置。这种离心卵显示四个细胞质层：一个大的离心卵黄区，一个狭窄的透明区，一个富含蛋白质的层，和一个在向心极的小透明区。在离心卵细胞内注射钙特异性发光蛋白水母发光蛋白的细胞质钙成像显示了一系列重复的钙波受精后。大约70%的这些波开始在植物/收缩极区，这是类似的波的数量，以前发现在这个地区开始在未离心的鸡蛋。相比之下，只有大约25%的波开始接近位移的富钙层。从这个结果可以得出结论，主波起始位点不位移的离心力，取代皮层下，富含淀粉酶的部分肌浆。此外，观察到的动物-植物极性的皮质成分，如肌动蛋白丝和内质网已被保留离心后进一步表明，皮质成分位于植物半球-最有可能的内质网网络在皮层区域的肌质-参与启动重复的钙波在受精海鞘卵。
Ascidian eggs respond to fertilization with a series of repetitive calcium waves that originate mostly from the vegetal/contraction pole region (J. E. Speksnijder, C. Sardet, and L. F. Jaffe, 1990,Dev. Biol.142,246–249), where the myoplasm is concentrated during the first phase of ooplasmic segregation. This suggests that the myoplasm may be involved in initiating these calcium waves. To test this possibility, the starting position of the calcium waves was determined in eggs that had the subcortical, mitochondria-rich part of the myoplasm displaced by centrifugation. Such centrifuged eggs display four cytoplasmic layers: a large centrifugal yolk zone, a narrow clear zone, a mitochondria-rich layer, and a small clear zone at the centripetal pole. Imaging of the cytosolic calcium in centrifuged eggs that were injected with the calcium-specific photoprotein aequorin reveals a series of repetitive calcium waves after fertilization. About 70% of these waves start in the vegetal/contraction pole area, which is similar to the number of waves previously found to start in this area in uncentrifuged eggs. In contrast, only about 25% of the waves start close to the displaced mitochondria-rich layer. From this result it is concluded that the main wave initiation site is not displaced by the centrifugal forces that displace the subcortical, mitochondria-rich part of the myoplasm. Moreover, the observation that the animal-vegetal polarity of cortical components such as actin filaments and the endoplasmic reticulum has been retained after centrifugation further suggests that a cortical component located in the vegetal hemisphere—most likely the endoplasmic reticulum network in the cortical region of the myoplasm—is involved in initiating the repetitive calcium waves in the fertilized ascidian egg.